Contents

Introduction

The combination of jaundice and cystitis in a young patient should make you think of chronic ketamine abuse

Has analgesic properties as well as being an intravenous anaesthetic agent with very little risk of respiratory depression. Not used much in adults in the UK, although a commonly used anaesthetic agent in developing countries and in onsite emergency trauma treatment. It produces a dissociated state where the patient can still respond. Can be useful in the paediatric population as the airway reflexes are said to be less suppressed.

It is psycho-active leading to both recreational use (which runs the risk of inducing a severe cystitis) and attempts to use it as a rapidly acting agent in refractory depression[1][2][3]. Individual response in this last indication shows marked variability and may be related to differential metabolism between individuals[4]. The best evidence is for the dose 0.5mg/kg intravenously.[5]

Clinical Use

Indications

Anaesthesia - induction and maintenance

Administration

In clinical use it is usually given intravenously, but in 'recreational use' is often taken orally.

Special advice

Pharmacology

The drug is a racemic mixture. It blocks glutamatergic NMDA receptors.(S)-ketamine has a threefold higher affinity for the NMDA receptor than (R)-ketamine)[7]. There is upregulation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) subtypes with intracellular changes in protein expression, including the proteins mammalian target of rapamycin (mTOR) and brain-derived neurotrophic factor (BDNF). It actually interacts at multiple sites in the central nervous system, including NMDA and non-NMDA glutamate receptors, nicotinic and muscarinic cholinergic receptors, and adrenergic and opioid receptors( μ- and δ-opioid receptors but not κ-opioid receptors)[8].